The invention relates to an apparatus and method for insufflating fluid media, in particular CO.sub.2 gas, into a cavity of a human or animal body, where the fluid flows from a source under pressure via a pressure reducer to an intermediate vessel and by which the fluid medium is conveyed via a line provided with a shut-off valve into the body cavity and in which a pressure measuring device is provided with which the body cavity pressure is measured.
German Gebrauchmuster No. 75/08556 proposes an insufflator for the introduction of limited amounts of carbon dioxide gas into the human body, where via a first line the gas is supplied to the human body while the pressure adjusting itself in the body is being measured via a second line. This document states that an instrument-side pressure adjustment which corresponds to the pressure desired in the human body cannot be fixed exactly because of the backpressure which builds up in the first line and in the Veress needle. To avoid these disadvantages, the first and second lines are connected either with a double-barrel Veress needle or with two single-barrel Veress needles. Both lines are connected on the instrument side, the pressure produced in the body cavity being connected on the instrument side, the pressure produced in the body cavity being measured via the second line, which communicates with a pressure gauge provided in the housing. Use of such Veress needles, however, has the disadvantage that the feed aperture for the gas and the measuring aperture at the double-barrel Veress needle or respectively at the two single-barrel Veress needles are not identical. It may happen, therefore, that the gas supply aperture is separated from the measuring aperture by a body membrane, the fed gas inflating a body cavity without the pressure gauge indicating this fact. This danger is especially great when two single-barrel needles are used. On the other hand, the measuring aperture of the needle may become clogged by blood or tissue parts, for example, so that again no pressure variation will become visible on the pressure gauge. Such faulty indication naturally represents an increased risk for the patient, if not a life threatening situation.
In German Auslegeschrift No. 25 44 567 a gas insufflator is described where via a first line and a cannula the gas is introduced into the body cavity. This cannula is double-barreled, that is, the cannula is surrounded by a tube which distally opens into the body cavity and proximally is connected to a contact manometer via a measuring line. At a certain pressure this contact manometer closes a contact by which a valve disposed in the feed line is closed and in addition an alarm device is actuated. As in the above mentioned Gebrauchmuster, the openings located in the body cavity for introducing the gas and for measuring the pressure are not identical, so that here, too, clogging of the measuring aperture may occur. Thus the above mentioned disadvantages again are present.
What the two known devices have in common is that they are to pick up the pressure in the body cavity more exactly via a return line, making it visible on a display. It is only in the Auslegeschrift that the infeed is closed when a certain limit pressure is exceeded. If this limit pressure drops, this valve will be reopened, so that gas moves up into the body cavity again. This procedure, which replaces the manual operation of the insufflator by an automatic regulation, suffers, as has been said, from the danger of clogging of the measuring aperture and from the different arrangement of the feed and measuring apertures.
It is the object of the invention to provide a device for insufflating fluid media into human or animal bodies where the measuring aperture is prevented from clogging safely and which permits reliable determination of the pressure in the body cavity and possibly also the automatic regulation of this pressure.